Distillation of solid carbonaceous material



March 14, 1933. L. c. KARRICK 1,901,169

DISTILLATION OF SOLID CARBONACEOUS MATERIAL Filed May '7, 1924 2Sheets-Sheet l March 14, 1933. L. c. KARRICK 1.9019

DISTILLATION OF SOLID CARBONACEOUS MATERIAL I Filed May 7, 1924 2Sheets-Sheet 2 JNVE/VTOR ATTORNEY patented Mar. 14, 1933 PATENT OFFICELEWIS C. KARRICK, F SALT LAKE CITY, UTAH,

DISTILLATION OF SOLID CARBONACEO'US MATERIAL Application filed May '7,1924. Serial No. 711,554.

This invention relates to a process for the treatment of solidcarbonaceous substances for the purpose of removing all or anypercentage of the total volatileconstituents therefrom and, in the caseof coals, leaving the coke either devoid of volatile ingredients orstill containing any desired portion of the original volatileingredients. The coke has desirable kindling and burning propertles andwill burn smokelessly. A large quantity of ammonia may be produced fromthe nitrogen containing ingredients of the material being treated.Liquid hydrocarbons, commonly called oils or low temperature tars areobtained from the volatized ingredients and also a residual combustiblegas which may or may not carry in a vaporized condition fixed-gasgasoline which is similar in gravity and volatilityto casingheadgasoline obtainable from wet natural gas.

The invention will be described in connection with the heat treatment ofcoal, but it is to be understood that it is also applicable peat, woodor other solid substances classifiable as fuels broadly or substanceswhich may yield fuels.

The raw material is heated in a retort which may be of any desired sizeto effect successful mechanical operation but the economic operation isenhanced by the use of large volumetric capacity. The material beingtreated or destructively distilled passes F continuously through thedistilling section of the retort, but is charged at the top and the cokeis discharged at the bottom intermittently.

The material being distilled is sized by screening before delivery tothe retorts, each size being preferably treated separately in differentretorts to make possible greater plant capacity than would be the caseif mixed sizes of material were fed to all retorts.

superheated steam is used exclusively for the heat treatment of the rawmaterial. The process heat that is utilized is the sensible heat ofpartially de-superheatingthe steam and the steam leaves the retortstillsuperheated but ata lower temperature.

to other materials such as oil shales, lignite,

Thesuperheated steam is supplied at a temperature high enough to distillsuch volatiles as may be desired and is preferably between 1200 F. and1600 F. as it is within this range of'temperatures that a large part ofthe organic nitrogen compounds in the presence of steam are converted toammonia; this range of temperature is also suitable for carrying on thedestructive distillation.

Since steam is the only source of heat and only a part of the heat ofsuperheat of the s eam is available for use in distilling, only a, smallpercentage of the total heat of the steam is utilized in the retort.

A considerable part of the remaining total heat of steam discharged fromthe retort may be advantageously used to generate part of the freshsupply of steam required for the retort or preferably for a secondretort operating at a lower pressure, and the sensible 79 and latentheats of the coal volatiles may be used in the same way.

I may take advantage of the fact that vapors at different pressurescondense at diferent temperatures. The retorts described in thisspecification may operate in batteries or units of two or more, forexample, five retorts, and each retort may be maintained at a differentpressure from the others, the first being held at the highest pressureand 80 each one thereafter in the sequence or unit should be at asuccessively lower pressure. The pressure difference between the retortsshould be such that difference between the condensing-temperature of thesteam and coal volatiles and that of the freshly generated steam ispreferably made equal or nearly so between each pair of retorts, thelast retort operating at atmospheric pressure or preferably belowatmospheric pressure in order that maximum advantage may be taken of thesteam discharged from one retort in producing stcam'for the succeedingone. The

vapors and gases from the first retort are conducted into a heatexchanger and allowed to condense, thereby giving up their heat to thewater surrounding the tubes and generating fresh steam preferably at alower pressure, and this new steam will be conducted through a secondsuperheater and into the next retort with an additional supply of steamif necessary.

My process also takes advantage of the sensible heat of the coke toprovide part of the heat necessary to carry on the distillation. Thismay be accomplished by dividing the steam supplied to the retort beforeit reaches the superheater. Part of the steam goes through thesuperheater and into the retort at approximately its center, Whereas thebalance of the steam passes into the bot-- tom section of the retort andby its counter current flow to the direction of flow of the moving coke,it abstracts the heat from the coke and the steam becomes superheated toapproximately the same temperature as the balance of the superheatedsteam by the time it reaches the point of introduction of the lattersteam. The steam used for this heat recovery purpose may be wet steam soas to insure ample quenching of the highly combustible coke formed.There will be a saving of fuel if the steam used for heat recovery isgenerated by water coming into contact with the hot coke in the bottomof the retort instead of being generated in the boiler or evaporator. I

In the accompanying drawings: 0 v Figure 1 is a diagrammatic sectionalside view of a retort and its appurtenances.

Figure 2 is a similar View of a battery of retorts and some of theirinter-connections.

Sized coal or material to be treated is delivered to the retorts fromthe carrier 1,

which is cylindrical in shape, has a hopper top and a hinged bottom; thecapacity is equal to the volume of the charging bin 3.

The vapor-tight closure or cap 2 of the re opened and the'vapors areexhausted into one of the following evaporators about at atmosphericpressure, thereby not Wasting the heat of the exhausted vapors. Thecarrier with its load is then lowered into the bin 3 until nearlyresting on the bin bottom or slide 4 and then the carrier bottom isreleased and the carrier raised, thus permitting the charge to slideinto the bin with the minimum amount of abrasion to the coal or materialcharged. It is assumed that the retort has been in continuousoperation-while the charging operation just described was accomplished,and therefore the gate or slide l. at the bottom of the bin was closedand the retort proper 7, 8, was full up to the slide 4 'During thecharging operation the distillation has been in continuous progress andtho charge-level has gradually settled from just below the slide 4 andis gradually approaching the level of the vapor oft-take 6. As soon asthe bin 3 is filled, which should not require more than one minute, thetop 2 is closed,

the valve 30a connected to a source of fairly high pressure, as thevapor line 34: orseparator 29, is opened to partially balance thepressure against the lower side of the slide 4, and then the slide I isopened, thereby allowing the auxiliar bin 5 to fill up from 3. The bin 3now remains closed at the top until the charge-level again sinks belowthe slide at, whereupon the charging operations are repeated.

Since the flow of charge is continuous and uninterrupted in its passagethrough the re torting shaft 7, 8, it is proper that the flow ofsuperheated steam from its source should be constant, and therefore, thesupply of steam and its temperature are fixed when the" plant is putinto operation once a proper balance between supply of steam and rate offeed of the charge is determined.

Retorting shaft 7 is made, preferably, of steel plate, designed to suitthe strength requirement of each retort, which obviously will bedifferent, and may be of slightly increasing dimensions toward thebottom, as

shown. The dimensions of the shaft 7 should be such that there will beample time allowed for the largest lumps of coal composing the charge tocompletely distill while passing down through the retort 7, 8, and thatthe steam passing off from the retort will have part of its heat ofsuperheat abstracted but leave it still superheated to avoid possibilityof any appreciable condensation taking place in the retort.

The vapor off-take 6 is a'manifold type with tour or six branches 6aleading off from the retort at equidistant points around thecircumference of the retort. The branches rise a few inches from theirjunction with the retort wall in'order that no fine material of thecharge will be blown out into the vapor line 34 by the current of theexhaust vapors and gases.

The retort shaft will be hottest at the point of introduction of thesuperheated steam and if the retort walls are properly insulated againstradiation, the walls at all points will have the same temperature as thesteam in contact with them. In order that the high temperaturesnecessary for the distillations will not make necessary frequentshutdowns for repairs to the retort, it is desirable that the portion ofthe retort walls that will be exposed to the highest temperatures shouldbe made of a material which will give long service. The retort is The 1each other at the top in order that the material passing them will notbe crushed or disintegrated as would be the case if the rolls turned inthe direction to cause the material to pass between them. The rolls turnat a uniform speed and may be provided with gears, not shown, so that ifdesired, the rate of feed can be changed.

The parts of the shaft below the inlet 9 for superheated steam and abovethe inlet 12 for saturated steam, including the section 10 above thefeed regulating mechanism 11, and also including the space about thefeed regulating mechanism 11, are cooling or heat recovery sections ofthe retorting device. The section 10 of the retort should be long andmay be fully as long as the section 7, 8. The discharge from the feedregulating mechanism 11 falls directly through the gate or slide 14which is just above the discharge bin 15, and falls into the. dischargebin 15, until this bin is full, or full nearly, up to the slide 14. Asabove described saturated steam at the same pressure as the superheatedsteam, flows into the section 13 of the shaft through the port 12. Gasadmitted through the valve 31 will have the same effect. As thissaturated steam passes up counter-currently to the downcoming treatedmaterial, it first becomes dry steam and then becomes superheated. Witha proper adjustment of the supply of saturated steam, the steam admittedat the port 12 will arrive opposite the ports 9 in approximately thesame degree of superheat as the steam admitted from the superheaterdiagrammatically shown at 21. The coke will then be reduced intemperature from the maximum value at the level 8 down to thetemperature of saturated steam, at the pressure held in the retort, andthereby almost all the residual sensible heat of the coke will have beenabstracted and this same heat also will have been used to help distillthe coal in the retort.

The discharge bin 15 is closed at its bottom by a cap 16 which may be ofthe same construction as the cap 2 at the top of the feed bin 3. Thedischarge bin 15 is also provided with a pressure-relief valve 31connected to the same conduit as the pressure-relief valve 30 of thefeed bin 3.

lVhen the slide 4 has been closed, due to the feed bin 3/being emptied,the discharge bin 15 should be full of the treated material;.

therefore the slide 14; is closed. The discharge bin 15 is now opened bytaking off the bottom cap 16. after momentarily opening itspressure-release valve 31, corresponding to the relief valve 30 of thebin 4: and the charge is allowed to run out. The cap 16 is quicklyclosed. the valve 31a corresponding to the relief valve 30 of the bin 4opened nunnentarilv again to restore the pressure in the discharge bin 1and the slide 14 is opened, thus allowing the treated material which hascollected above the slide 14 to drop into the discharge bin 15.

The flow-dividing valve 19 is quick acting and will vary the flow in anyproportions between the two steam feeding ports. This coke, but in suchan amount that no free moisture will be left in the coke. It ispreferable that saturated steam carrying atomized water should be used.The best results will be attained in the use of partially devolatilizedcoal as a smokeless fuel, if it is used in a physically dry state, andtherefore too much water carried into the retort with the steam may beobjectionable because it will leave the treated material wet.

The mixed vapors and gases are conducted from the retort by the vaporline 34 into the heat exchanger, waste-heat boiler, or evaporator 26.Water from the feedwater heater of the steam plant or any otheradvantageous source of hot water, is fed into the evaporator 26 by thepipe 27. This pipe is shown for convenience of illustration as providedwith heat-conducting fins 35. Annular bafile plates 36 extend inwardfrom the wall of the heat-exchangerl26 between the fins. By properregulation of the flow of water practically all the vapors willbe causedto condense and the gas cooled, and as a result, steam will be generatedfrom the water and this steam will be used in the following retort. Thegeneration of steam for each retort after the first one may. beaccomplished in this manner, and in'order to effect the necessary heattransfer in generating the steam. it is'necessary that there be adifference in temperature maintained in the evaporators 26 between theincoming mixed vapors and gases and the outgoing freshly produced steam,and this may be effected by maintaining correspondingly differentpressures. This pressure regulation is controlled by automaticpressure-regulating throttlevalves 28.

x In the example shown in the drawings (Fig. 2) with five retortssucessively arranged the successive pressures may be lower than in thesuccessive retorts from left to right. Should it be desirable in anyinstance to carry the pressures in some of the retorts to a point belowatmospheric pressure then vacuum pumps 37 would be needed as shown inrelation to the fifth retort. The vacuum pumps to draw off the fixedgases and deliver them against the higher external atmospheric or stillhigher pipe line pressure.

Each; separator 29 receives the discharge of combined condensates andcooled gases under the pressure that exists in the correspondingevaporator. Sufficient volume is provided to permit ample time for themaximum cleanness of separation of gas, oil and water to be effected.The gas produced may be sent to a storage or scrubbing tank 38 and usedfor any desired purpose. The oil may be refined, and the condensed watertreated for the recovery of the valuable material it carries,principally nitrogen compounds.

Utah coal from the Castle Gate coal district was heated by steamentering at a temperature of 1100 to 1500 F. in a continuously fedretort according to the procedure described above. A very large part ofthe heat from the heated product was recovered. At the temperature thusobtained little or no decomposition took place of the hydrocarbon orother volatile products. The coal yielded oil at the rate of 35 gallonsoil per ton of coal.

This oil was separated by fractional distillation into Per cent Motorfuel distillate 22 Heavy motor engine distillate 22 Cracking stock 25balance, lubricating oil, wax distillate, and pitch residue. oil therewas separated 20%of tar acids suitable for froth flotation operationsand for wood preservation. Two different runs of run-of1nine coal fromtwo different collieries yielded similar results both when distilled byatmospheric pressures and at higher pressures. The coal yielded inaddition 3500 cubic feet of 950 B. t. 11. gas per ton of coal. The gascontained very little illuminants rich in paraflin hydrocarbons andhydrogen. The residual coal was as easily kindled as the raw coal. underfavorable conditions capable of being lit with a match. By the process asimilar easily kindled coal was made from anthracite coal commerciallysold in the Pittsburgh market, the small amount of oil and gas producedbeing allowed to waste. Quenching the treated coal from the retort bydry steam arrested the tendency to spontaneous combustion that it wouldotherwise possess, although its property of being easily kindled was notdestroyed.

Having thus described certain embodiments of my invention what I claimis:

1. The combination with a retort. of means for distilling the contentsthereof by superheated steam, a second retort. means for heating thesecond retort by steam, a heatex- ,change device between the retorts.means in said heat exchange device to supply water to be heated to makesteam for said second re tort, and connections to and from theheat-exchange device whereby the discharged steam and vapors and gasesfrom the first retort enter the heat exchange device. and steam for thesecond retort is produced in the heatexchange device.

2. The combination with a retort. of means for distilling thecontentstl1crc )fby internal- From one lot of the crudely suppliedsuperheated steam under high pressure, a second retort, means fordistilling the contents thereof byinternally supplied superheated steamunder lower pressure, a heat-exchange device between the retorts andhaving on its respective sides the pressures of the correspondingretorts, means in said heat exchange device to supply water to be heatedto make steam for said second retort, off-takes for liquid and gasconnected to said exchange device for the products of the first retort,and connections for carrying steam from the heat-exchange device to thesecond retort.

3. The combination with 'a retort, of means for heating it internally bysteam, a second retort. means for heating the second retort internallyby steam, a heat-exchange device between the retorts, means in said heatexchange device to supply water to be heated to make steam for saidsecond retort, and connections to and from the heat-exchange devicewhereby the discharge steam from the first retort enters theheat-exchange device and steam for the second retort is supplied fromthe heat-exchange device.

i. The combination with a retort, of means for heating it internally bysteam, asecond retort, means for heating the second retort by steam, aheatexchange device between the retorts, a water supply for said heatexchange device, off-takes for liquid and gas connected to said exchangedevice for the products of the first retort, valves for said off-takesto control the pressure at their side of the exchange device, andconnections for conveying steam to the second retort from theheat-exchange device.

5. In aretort the combination of a charging device at the top and adischarging device at the bottom, a vapor line for leading away vaporsmaterially below the charging device, a steam supply, means for dividingthe steam supply, means for superheating one part and delivering it tothe retort materially below the vapor line, and means for adding waterto the other part of the steam supply and delivering it to the retort ata zone still further down in the retort, whereby the steam at the lowerpoint of delivery receives heat from the charge as it rises, to thepoint at which the superheated steam is admitted.

6. The process of distilling solid carbonaceous material which consistsin feeding the material through a retort where it is exposed tosuperheated steam, distilling and discharging volatile products,condensing the volatile products and steam in a heat-exchange device atsubstantially retort pressure. boiling water by said device to produceanother supply of steam at lower pressure, superheating part of theother supply, and heating carbmiaceous material in a second retort fromsaid other supply at said lower' PIGSSU re.

7. The process of distillin solid carbonaceous material, which consistsin feeding carbonaceous material simultaneously through a plurality ofparallel retorts at different pressures, heating a first retort bysuperheated steam, passing the resulting vapors through a heat-exchangedevice that is provided with a supply of water thereby generatinganother supply of steam at lower pressure, and heating a second retortfrom said other supply.

8. The process of operating a plurality of retorts for distilling solidcarbonaceous material, which consists in heating a first re tort bysuperheated steam at a relatively high pressure to distill oif volatilematerial, passing the resulting vapors through a heat-exchange devicesupplied with water to furnish another supply of steam at a lowerpressure to heat a second retort, to distill ofi another lot of volatilematerial, and. passing said other lot of distilled vapors through asecond heat-exchange device supplied with water to furnish anothersupply of steam at a still lower pressure to supply heat to a thirdretort.

9. The process of operating a plurality of parallel retorts to recovervolatile material from solid carbonaceous material, which consists inheating a first retort with superheated steam, condensing the steam andresulting volatile material in a heat-exchange device supplied withwater to produce an other supply of steam at lower pressure from thelatent heat so released, and delivering this steam to a second retort toheat carbonaceous material therein.

10. The process of operating a plurality of parallel retorts to recovervolatile material from solid carbonaceous material, which consists inheating a retort with superheated steam, condensing the steam andresulting volatile material in a heat-exchange device supplied withwater to produce another supply of steam, conducting said steam througha second retort to which additional heat is also supplied, andcondensing the volatile material in the second retort.

' 11. The process of distilling coal, which comprises passing lumps ofcoal through a chamber and heating it by means of super-, heated steam,one part of which is introduced into direct contact therewithintermediate the ends of said chamber and another part of which isobtained by saturated steam after contacting with the hot solid residue,the

another part of which is obtained by saturated steam after-contactingwith the hot residue, the amount of the saturated steam being such thatthe superheated steam therefrom will have approximately the sametemperature as the other part of the steam when it reaches the placewhere the other part of the steam is introduced.

13. The process of distilling solid carbonaceous material, whichcomprises separating crushed material into sizes, feeding differentsizes to different retorts, distilling the contents of each retort bysuperheated steam in contact with the material, maintaining difierentpressures in the retorts, using the waste heat of vapors and gases fromone retort to produce steam for a succeeding retort at a lower pressure,and using the coarser mate rial in the retort of lower pressure.

14. The process of operating a plurality of retorts for distillingsolidcarbonaceous material, which consists in heating a first retort bysuperheated steam under high pressure at a relatively high' temperatureto distill off oil and gases, passing the resulting vapors and gasesunder pressure into a heatexchange device supplied with water to furnishanother supply of steam at a lower pressure to heat a second retort, todistill oil an-- other lot of oil and gases, and passing said other lotof distilled vapors and gases under pressure into a second heat-exchangedevice supplied with water to furnish another supply of steam at a stilllower pressure to supply heat to a third retort, and withdrawing theincondensible gases under pressure from said heat-exchange devices.

In testimony whereof, I have aflixed my signature to this specification,

LEWIS C. KARRICK.

temperatures of the portions of steam being substantially equal to eachother where they contact with the coal that is undergoing treatment.

12. The process of distilling coal, which comprises passing lumps ofcoal through a chamber and heating it by means of superheated steam, onepart of which is introduced intermediate the ends of said chamber and

